1. Field of the Invention
The present invention relates to a grommet, and in particular to a grommet having a waterproof and soundproof structure to improve installation workability of the same on a panel for vehicles or the like.
2. Description of the Prior Art
Conventionally, there have been provided a variety of grommets each of which is fitted on a panel of a vehicle or the like with the assembly of a wire harness inserted through an inserting hole formed in the panel.
FIG. 5 shows an example of conventional grommets. In FIG. 5, a grommet body 1 is made of an elastic material and includes a cylindrical portion 1a of a small diameter for supporting a wire harness 2 in a manner such that the wire harness is inserted through the inner hole of the cylindrical portion 1a. The grommet body further includes an expanded diameter portion 1b which communicates concentrically with the small diameter cylindrical portion 1a. The expanded diameter portion 1b is provided with a flange 1c at its peripheral edge, and the flange 1c has an annular groove 1d formed therein. A panel 3 has an inserting hole 3a formed therein generally corresponding to the expanded diameter portion 1b, and the annular groove 1d of the flange 1c is engaged with the edge of the inserting hole 3a defined in the panel 3 thereby to tightly hold the grommet body 1 fitted on the panel 3.
When assembling the grommet body 1 with the wire harness 2 which is composed of electric wires 5, the wire harness 2 is inserted through the small diameter cylindrical portion 1a and the expanded diameter portion 1b in the first stage, and then a filler 4 made of a liquid setting material is filled into the expanded diameter portion 1b thereby to securely holding the wire harness 2 in the grommet body 1. After the filler material 4 has been set, the assembly composed of the grommet body 1 and the wire harness 2 insertingly held therethrough is fitted into the inserting hole 3a of the panel 3.
In the grommet body 1 mentioned above, a gap between the outer periphery of the wire harness 2 and the inner surface of the grommet body 1 as well as gaps made relative to each other between the electric wires 5 which compose the wire harness 2 are filled with the liquid filler setting material 4 to improve the waterproof and sound-proof properties.
In the grommet thus composed, however, there is a problem in workability in that, when the assembly composed of the grommet body 1 and the wire harness 2 insertingly held thereby is fitted into the inserting hole 3a formed in the panel 3, it is not easy to engage the edge of the inserting hole 3a of the panel 3 with the annular groove, 1d formed in the flange 1c of the grommet body 1. This is because, when the liquid filler material 4 is once hardened to be solid, it is difficult to deform the grommet body 1 in the area containing therein the filler material 4 which has already been set.
On the other hand, one may choose a structure in which the small diameter cylindrical portion 1a is strapped up with a tape to tightly hold the wire harness 2 without using a liquid filler material. In this structure, it is then difficult to ensure sufficient waterproof and soundproof properties as compared with the structure in which the filler material is utilized.
Furthermore, since the wire harness 2 and grommet body 1 are tightly bonded with each other via the hard filler material 4, when an external force such as a tension for example is applied to the wire harness 2, the applied external force will be transferred to the grommet body 1 through the filler 4, which may sometimes cause the grommet body 1 to be removed from the panel 3.